Communication system



Cv R. DOTY Dec. 5, 1939.

COMMUNICATION SYSTEM Filed Feb. 12, 1938 3 Sheets-Sheet l ATTORNEY Dec.5, 1939. c. R. DOTY 2,131,939

COMMUNICATION SYSTEM Filed Feb. 12, 1938 3 Sheets-Sheet 2 NVE TOR 25% BYV ATTORNEY & Ef e:

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E G1 I n 5 n Dec. 5, 1939. c. R. DOTY 2,181,989

COMMUNICATION SYSTEM Filed Feb. 12, 19:58 s Sheets-Sheet 3 ATTORNEYFIGS.

Patented Dec. 5, 1939 PATENT OFFICE 2,181,989 COMMUNICATION SYSTEMCharles R. Doty, Binghamton, N. Y., assignor to International BusinessMachines Corporation, New York, N. Y., a corporation of New YorkApplication February m, 1938, Serial No'. 190,246

7 Claims.

This invention relates to communication systems and more particularly tosynchronously operated systems, one well known type of which is theprinting telegraph system.

One of the objects of the present invention resides in the provision ofa synchronous system in which a predetermined number of impulses, namelythree, is employed to represent all characters to be transmitted andreceived.

Another object of the present invention resides in the provision of asynchronous system in which different characteristics are imparted tothe impulses, thereby increasing the number of character permutationsand effecting the selection of a single circuit for each permutation fora plurality of selection circuits at the receiver.

Another object of the invention resides in the provision of controlmeans at the receiver which is conditioned by the first of a pluralityof impulses representing a character to control selection means, thelatter in turn being partially conditioned by the second impulse andcompleted by the third impulse ata differential time in the cycle, toeffect the completion of a single character selection circuit.

Still another object resides in the provision of a synchronous system inwhich control members are used to initiate impulses at the transmitter,a predetermined number of these, namely three, being operated for eachcharacter to be transmitted, and a common control member being operatedsimultaneously, regardless of the character to be transmitted, toinitiate a control impulse to effect the engagement of the normallylatched members of a rotary distributing means with its synchronouslydriven members so as to condition a predetermined number of controlcircuits for transmitting the character impulses.

Various other objects and advantages of the invention will becomeobvious from the following description of one form of mechanismembodying the invention or from an inspection of the ac companyingdrawings; and the invention also constitutes certain new and usefulfeatures of construction and combination of par-ts hereinafter set forthand claimed.

In the drawings:

Fig. 1 shows, in part one type of transmitting and receiving controlunit. 1

Fig. 2 is a detail perspective of an operating mechanism of the imitshown in Fig. 1.

Fig. 3 shows a rotary distributor means with one type of clutchingarrangement which may be employed at the transmitter.

Fig. 4 is a circuit diagram for the transmitting station.

Fig. 5 is a circuit diagram for the receiving station.

For illustrative purposes, this invention is shown as embodying a wellknown type of recording unit, which may be similar in construction tothe Electromatic typewriter, shown and described'in detail in U. S.Patent No. 1,777,055, and hence requires only the following briefdescripion. a

I Referring to the drawings and particularly to Fig. 1, well known meansare provided for actuating the type bars l6, comprising a constantlyrotating roller Hi, cooperating with a series of individual poweru'nitseach comprising a cam II, the engagement of the cams being controlledselectively by the character key bars l1.

Any suitable means may be provided to rotate the power roller, in thedirection indicated by the arrow, which is adapted to cooperate with tworows of cam units arranged in the front and rear of the roller. Thecamll may be provided to be pivoted on one arm of a bell crank lever l2which is pivoted in the frame of the recording unit, as indicatedgenerally by reference character i3, the other arm of the said bellcrank lever being operatively connected with an arm of bell crank leverM by means of link l5. Another arm of said lever I4 is connected to thetype bars IS in a well known manner, so as to effect operation of thetype bars or any other suitable means connected to the bell cranklevers-upon selective operation of the controlling key bars H.

The pivoted bell crank lever I2 is operated by r the associated cam Hwhenever the latter engages the driven roller; the engagement of the camwith the roller is controlled by means of the associated control key barI! in a manner which will now be briefly described.

Referring now to Fig. 2, the cams occupy normally the positions as shownin this figure, which represents one of the rear bank of units. In thisposition the impeller-arm I8 is urged, by the associated coil spring it,against one of the impeller lugs 20, which at the time is in the lowerposition, and tends to turn the cam I l in a clockwise direction. Thisis prevented, however, by the engagement of one of the detents 2| on thecam, with the upper stop leg 22 on stop lever 23. If, however, thecorresponding key bar is operated, the bifurcated lower end (Fig. 1) ofextension arm 24 associated with one of the said key bars l1 engages anarm 25 at the upper end of the stop lever 23 which extends laterallythrough an opening in the bell crank lever l2. The arm 25 of the stoplever 23 is then swung rearwardly or to the left as viewed in Fig. 1about the pivot 26 and its lower end forwardly or to the right as viewedin this figure, thus releasing the cam, which then turns under theinfluence of the spring urged impeller-arm l8. In doing so the upperserrated lobe of the cam is brought into engagement with the powerroller which turns in a counterclockwise direction and therefore causesa continued rolling movement of the cam other mechanism with which thecam unit may be connected.

After the high point of the cam is passed the cam loses contact with theroller, but the said impeller-arm it tends to continue the rotationthereof by engaging the second impeller-lug 29 of cam ll until thesecond detent 21 engages one of the stop lugs. Since the half rotationof the cam consumes only a small fraction of a second, it is 'difiicultto release the key bar within this short interval, so that it is thelower lug 28 which is first engaged, but upon the release of the key barand the return of the stop lever 23 to normal position, this lug 28disengages the detent, whereupon the impeller-arm rotates the camslightly, and the said detent then engages the upper stop lug 22.

It is obvious then that depression of a key bar ,releases the revolublymounted cam to engage,

and be actuated by the power roller in turn operating the associatedbell crank lever and its attached links to cause the associatedmechanism such as the type bars and other operating mechanisms, to beoperated. It is to be understood that an individual camunit is providedfor each type bar or other functional mechanisms associated therewith.

The action of the cam mechanism has been described with respect to oneof the rear bank of cam units; in the case of those of the forward bankthe operation is analogous, but the (11160. tion of movement, and theorder of operation of the stop lugs, is reversed. For example, if thebifurcated arm Ma is positioned to engage the arm 25a at the upper endof stop lever 23w by virtue of operation of the associated key bar,thesaid arm is positioned rearwardly or to the left as viewed in Fig. 1,and the lower end of the. stop lever 23a is moved forwardly, that is, tothe right as viewed in said figure. This said operation is efiective torelease the cam, by virtue of positioning the lower stop lug 2811. outof the path of detent Zia, thus permitting the spring urged impeller armita to rotate the cam slightly in a clockwise direction to effectengagement of the lower lobe' of cam H and the power roller. Uponcompletion of a half revolution of the cam H, the second detent 21aengages first, in the upper stop lug 22a while the stop lever 23a is inan operated position, but upon'release of the associated key bar and thereturn of the said stop lever to normal position, this lug 22a.disengages the said detent and the impeller-arm rotates the cam slightlyso that the said detent then engages the lower stop-lug 28a, as shown inthe figure. In ,this manner the bell crank lever i211 is rotated aboutthe pivot l3a to operate the associated type bar or any other mechanismassociated therewith. For further structural details of the cam units,reference should be made to the above mentioned patent.

When the mechanism described above is used as a transmitter, the cam II,when released, is arranged to operate a plurality of control memberssuch as the contacts generally designated 10. An assembly of thesecontacts is located in the path of each of the cams, so that thedepression of any key bar i? will result not only in the actuation of atype bar IE but also in the closing of a corresponding contact assemblyfor a very brief interval of time. The closing of these conualdepression of the key bar l7.

tacts effect the initiation of impulses to represent the character to,betransmitted. I

, When the mechanism described above is used as a receiver, asolenoid 30is associated with each key bar H so that upon energization of thesolenoid the key bar will be drawn down and causethe corresponding typebar It to be actuated for the purpose of recording the characterreceived. Obviously, the operation of the mechanism resulting from theenergization of the solenoid 30 will be the same as thatresulting fromthe man- In the present system, rotary distributor units are located atthe'transmitting and receiving stations and are vdriven in synchronismby synchronous motors or other suitable means well known in the art. Onetype of rotary distributor unit, generally designated 40 (Fig. 3), isshown to comprise two commutators and two control rings each havingbrushes associated therewith. The commutators, designated il and 42, areidentical in every respect and are electrically insulated from 'eachother by any suitable means. Commutator brushes 43 and 44 are mounted onan arm 45 and are insulated from each other and the arm by insulatingmaterial such as 46. The brush arm 15 is fixed to a constantly rotatingshaft 41 which is driven by a synchronous motor (not shown). Thus thecommutator brushes are caused to rotate continuously around theperipheries of the commutators ll and t2 and engage successively theindividual conductive segments di-I to 6 and it-4 to 6 respectively in amannerv well known in the art.

The control rings, designated 48 and as, are also electrically insulatedfrom each other and are provided with insulating segments 50 and 5!respectively, the purpose of which will be described later in connectionwith the electrical circuits of the system. Two pairs of insulatedbrushes 52 and 53 are mounted on a brush arm 54 and are associated withcontrolrings 48 and 49 respectively. The brush arm 56 is associated witha clutching arrangement, and is thereby held in a latched positionexcept when the clutch coil 55 is energized by a control impulseautomatically sent to it simultaneously with the initiation of characterimpulses to be transmitted. This feature will be explained in detaillater in connection with the electrical circuit diagram of thetransmitting station. Upon momentary energization of the clutch coil 55an arm 56 is displaced to the left and allows a dog 51 to be releasedand, under the impetus of spring 58, the dog will bear on the surface ofa clutch member 59 pinned to the continually running shaft 41 until apredetermined time, near the end of the rotary distributor cycle inwhich the clutch coil was energized, when the dog 5'! will engage in asingle tooth 60 of the clutch member. Once engaged with the clutchmember, the dog will remain engaged and drive its connected mechanismthrough one cycle of operation, at end of which it will latch up onlatching point 6! of arm 56. The dog 51 is connected by means of acollar .62 to the control ring brush arm 54 and consequently with eachengagement of the dog in the clutch member 59, the control ring brusheswill be rotated through one complete cycle around the periphery ofcontrol rings. This operation is repeated for each character to betransmitted.

At the receiving station, a rotary distributor unit similar to that atthe transmitter is employed with the exception that no clutchingarrangement is provided, and the receiving control ring brushes arecaused to rotate continuously in synchronism with the receiving com- 1mutator brushes by having the controlling brush arm as well as thecommutator brush arm fixed to the continuously rotating shaft. Thepurpose of the control ring clutch employed at the transmitter was tohold the control ring brushes latched up so that brushes 52 would reston the insulated portion 58, of control ring 48 to prevent the sendingof stray impulses over the line due to commutator brushes 43 and 44continuously traversing th commutator segments. How this accomplishesits purpose will become apparent from the circuit diagram (Fig. 4) andthe description to follow. It is evidentthat if these stray impulses areprevented from getting out to the line from the transmitter, thereshould be none to guard against at the receiver, so that a receivercontrol ring clutch in this system is not necessary.

A circuit diagram which may be used at the transmitting station is shownin Fig. 4 and will .now be described with reference to that figure.

As has been previously explained, a plurality of control members such ascontacts I8 (Fig. 3) are operated for each character to be transmittedbut only four such control member groups (10, II, I2 and 13) are shownin Fig. 4, that being considered representative of the entiretransmitter circuit for purposes of explanation. Impulses initiated fromthe operation of a control member group are stored up and controlled bymeans of twelve relays designated as RI to R-I2 inclusive. These relaysare of the double-wound type, each having an energizing coil and aholding coil.

Assumed, for example, that A is the character to be transmitted. Whenthe character key bar for the character A is depressed, contacts ID areclosed for a brief interval of time as previously described, and fourcircuits are completed. A circuit is established from ground 80, contactIlla now closed, conductor BI, clutch coil 55, to grounded battery 82,thus energizing the clutch coil. At the same time circuits are completedto energize relays R-I, R3, and RIIJ. The R,I relay is energized by acircuit from contact 10b through conductors 83 and 84, R-I relay coil,and via common conductor 85 to grounded battery 82. The R-3 relay ispicked up by a parallel circuit from contact 10C, via conductors 86 and8! to the R--3 coil, common conductor 85 to grounded battery 82. Anotherparallel circuit energizes the R,III relay as follows: contact 10d,conductors 88 and 89, RI9 coil, common conductor 85, to grounded battery82. These relays are each provided with three contacts designatedgenerally as 98, 9| and 92, which close when the coils of these relaysare energized. Contacts 90 of relays R-I, R-3 and R-Il] close to provideholding circuits for the coils of these relays as follows: groundedbattery 82, common conductor 85, coils of relays R I, R-3 and R-I0,contacts 90 of these relays, conductor 93, brushes 53 on control ring 49to ground 94. This circuit holds relays R-I, R--3 and RI0 energizeduntil a point after the signals have been sent to the line when brushes53 pass on the insulated portion 5| of their associated ring 49.

Contacts 9| and 92 of the above relays also close upon energization ofthese relays to prepare circuits between a direct current source ofpotential such as battery 95 and transmitter commutator segments 4II,4I-3, and 42-2. These circuits are allowed to be completed when brushes52 pass off the insulated portion 50 and on to the conducting portion oftheir associated ring 48. The polarity of the outgoing impulses will beplus on brush 43 and minus on brush 44 from segments I and 3, and minuson brush 43 and plus on brush 44 from segment 4. The circuits connectingbattery 95 with commutator segments for impressing these polarities isas follows: Positive side of battery 95, conductor 96, contacts 9| ofrelays RI and R3, to commutator segments 4II and 4I-3 respectively; andfrom negative side of battery 95, conductor 91, brushes 52 now onmetallic portion of ring 48, conductor 98, contacts 92 of the R-I and R3relays, to commutator segments 42-I and 42-3 respectively. Also, for theimpulse through the R,I8 relay, the circuit runs from the positive sideof battery 95, conductor 96, contacts 9| of the R |0 relay viaconductors 98a and 99 to commutator segment 422; and

from negative side of battery 95, conductor 97,

brushes 52, ring 48, via conductor 98 to contacts 92 of the R,-I9 relay,conductors I88 and NH, to commutator segment 4I4. Impulses are sent overthe line from the segments upon which the potentials were impressed asbrushes 43 and 44 pass over these segments.

A circuit diagram suitable for use at the receiver is shown in Fig. 5.With this circuit arrangement a total selection of 48' characters ispossible from permutations of three impulses representing eachcharacter. The selection is effected by the use of relays, each with anenergizing coil and a holding coil, a rotary distributor unit similar tothat used at the transmitter without the clutch attachment, a polaritydistinguishing means for the incoming impulses such as polarized relayII 0 (Fig. 5), a plurality of control and selection circuits, and asolenoid for each of the character keys. Assuming a synchronous system,commutator brushes III and H2 will be rotating correspondingly tobrushes 4| and 42 of the transmitter, segment for segment. Also receivercontrol ring brushes H3 and H4 will be rotating continuously in fixedrelation with brushes III and I I2 as has been previously explained.

In receiving the character A, to continue with the above example, thefirst impulse received is the impulse from transmitter segment 4I-I.

, This impulse was negative to the line leading from brush 44 andpositive to the line leading from brush .43 at the transmitter.Consequently, at the receiver, polarized relay I 0 is caused to beenergized and shift its armature I01 to the left closing contacts I88and passing current through brush III to segment II5-I, conductor II'I,R-I3, conductor I I 8 to the other side of the line, thus picking up theR-I3 relay. A holding circuit for this relay is established through itscontacts 9 from grounded battery I20, via conductors |2I to R-I3' coil,contacts 9 now closed, via conductor I 22 to brushes II4 on metallicportion of receiver control ring I24 to ground I25. Multiple contactsI26 associated with relay RI3 close, connecting relays RIl to R28 andR--24 to R-21 inclusive to segments 3, 4, 5, and 6 of the receivingcommutators II 5 and H6 respectively.v The next impulse will Thecontacts I29 grounded battery I20, via conductors I30 and I3I to R-IIcoil, contacts I29 now closed, via conductor I22 to brushes II I onmetallic portion of ring H4, to ground I25.

With the energization of relay RI'I, contacts I33 also close to connectone side of six character key solenoids (A, B, C, D, E and F) to oneside of brushes l I3 which at this time are still on insulated portionI32 of ring I23. Consequently no circuit is as yet completed to one sideof these solenoids from grounded battery I20.

The third impulse to be received in the permutation representing thecharacter A will be of opposite polarity to the first two impulses.Polarized relay IIO will shift its armature I01 to the right, closingcontacts I09, and current will pass through brush II2, commutatorsegment II6 I, then via conductor I34 through contacts I26f to the R-ZBcoil, conductors I35 and H8, to the other side of the line. Contacts I36close to establish a holding circuit for relay R.-25 from groundedbattery I20, via conductor I2I to the Rr25 coil, contacts I36, conductorI22, brushes H0 now on conducting portion of ring I 20, to ground I25.

The energization of relay RF-25 causes the multiple contacts I31associated with it to close and thereby connect one side of sixsolenoids (A, N, T, Y, U and BS) to ground I38. A battery circuit is nowprepared through the coil of the A solenoid and will be completed whenbrushes II3 pass onto the metallic portion of ring I23. The circuit isas follows: grounded battery I20, via conductor I39 to brushes II3 onmetallic portion of ring I23, conductor I40, contacts I33, solenoid A,contacts I31 now closed, conductor MI, to ground I38. The solenoid A isthus energized and is adapted to operate a suitable recording means suchas has already been described. Immediately upon the completion of therecording portion of the cycle, the holding circuits for all relays arebroken by the receiver control ring brushes passing onto the insulatingportion of their respective control rings.

For any other character to be communicated, the operation of thecircuits is similar and can be easily followed from the abovedescription of the circuit operation for the character A. An example ofthe code which may be used in combining the impulses into permutationsrepresenting characters is given in the table below with polarities oneach segment of transmitting commutator 42 on which the impulses are tobe impressed.

segments A. N D Y mitting commutators. This method is so well known inthe art that further description is believed unnecessary.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single modification, itwill be understood that various omissions and substitutions and changesin the form and details of the device illustrated and in its operationmay be made by those skilled in the art without departing from thespirit of the invention. It is the intention therefore to be limitedonly as indicated by the scope of the following claims.

circuits, means under control of the distributor means in accordancewtih the first impulse received to condition a predetermined number ofsaid control circuits, means also controlled by the distributor meansoperating through one of the conditioned control circuits in accordancewith the second impulse received to condition a predetermined number ofsaid character selection circuits, and further means controlled by saiddistributor means operating through another of the conditioned controlcircuits to effect the completion of a single one of the conditionedselection circuits to select the character represented by said impulses.v

2. A communication system comprising, in combination, means to receive aplurality of impulses comprising rotary distributor means provided witha plurality of segments, control means cooperating with a predeterminednumber of said segments and arranged to be selectively operated inaccordance with the first impulse received by said distributor means, aplurality of groups of control circuits cooperating with the remainingsegments, one group of said control circuits being conditioned inaccordance with the operated control means, a plurality of groups ofselection circuits, means rendered operative upon reception of thesecond impulse from one of said remaining segments through its relatedcontrol circuit within the conditioned group to prepare a set of saidselection circuits, and means rendered operative upon reception of thesecond impulse through one of said conditioned control circuits relatedto another of said remaining segments to prepare another set ofselection circuits, thereby completing a single selection circuit whichis common to both sets of selection circuits.

3. A synchronous communication system comprising, in combination at thetransmitter, rotary distributor means including normally inoperativetransmission control rings and a constantly rotating commutator, aplurality of control circuits, key-controlled means for selecting apredetermined number of said control circuits for operation inaccordance with the depression of a character key, further meanscontrolled by the key at the same time for energizing another of saidcontrol circuits, clutching mechanism including a clutch magnet operatedupon energization of the last-mentioned circuit to cause thetransmission control rings to rotate with the commutator in apredetermined relation to bring the selected control circuits under thecontrol of said commutator for the purpose of transmitting characterimpulses at a differential time in the commutator cycle.

4. A synchronous communication system comprising, in combination at thetransmitter, rotary distributor means including a normally inoperativetransmission control means and constantly rotating commutator, aplurality of control circuits, means for selecting a predeterminednumber of said control circuits for the operation in accordance with'acharacter, means to select another of said control circuits at the sametime to render the transmission control means operative to subject theselected control circuits to the control of the commutator to transmitimpulses representing the character at a differential time in thecommutator cycle.

5. A synchronous communication system comprising, in combination at thetransmitter, a plurality of groups of control members and a plurality ofcontrol circuits associated therewith, means to operate a predeterminedgroup of said control members for selecting the related control circuitsfor operation in accordance with a character to be transmitted and foroperating one of said selected control circuits at the same time, anormally inoperative transmission control means provided with clutchingmechanism rendered operative upon the operation of said last mentionedcircuit to condition the selected control circuits,

and a rotating commutator cooperating with said selected circuits fortransmitting a plurality of timed impulses representing the character.

6. A synchronous communication system comprising, in combination at thetransmitter, means to initiate a plurality of impulses representing acharacter, a plurality of control circuits including a plurality ofrelays under the control of said initiating means and adapted to beselectively energized thereby in accordance with the character to storethe impulses to be transmitted, and a cyclically operating rotarydistributor means for transmitting the impulses including a rotarycontrol means for eifecting the deenergization of all relays at apredetermined time after the transmitting portion of the same cycle ofthe distributor means in which said relays were energized.

7. A synchronous communication system, comprising, in combination at thereceiver, control means and selection means each comprising a pluralityof relays, rotary distributor means for receiving character impulses anddirecting them to the control and selection means at a differential timein the rotary distributor cycle to selectively energize a predeterminednumber of relays therein, and rotary control means included in thedistributor means for efiecting the deenergization of all relays at apredetermined time before the end of the rotary distributor cycle.

CHARLES R. DOTY.

CERTIFICATE OF CORRECTION Patent No 2,181,989-

December 5, 1959.

CHARLES 'R. DOTY.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction ere-follows: Page 11,,sect ond column, lines 20 and 21, claim 1, for "the first impulsererality" read their polarities, aplurality; and that the said Letters-Patent should be read with this correction therein that the same mayconform to the record ofthe case in the Patent Office.

Signed and sealed this 2nd day of April, A; D. l9h0.

(Seal) Henry Van Arsdale, Acting Commissioner of 'Pate nts.-

